Sensors on civil structures, such as buildings, dams, and bridges and orthopedic implants, such as artificial hips and knees, have been limited because of the need to provide power for sensor operation and interrogation. In many of these applications retrieving sensor data precludes the use of batteries at the sensor or hardwired connections to the sensor. Very small spaces where common batteries will not fit, extremely harsh environments where common batteries would fail, and metallic hermetically sealed enclosures that would interfere with electromagnetic communication are among the many environments where sensor data retrieval is difficult.
Biomedical implants in which any sensor or electronic device must be hermetically sealed in a bio-compatible material such as titanium. It has been undesirable to use batteries for power because of the possibility of leakage. In addition, the implants must be as small as possible, limiting the size of batteries. Providing power to such sensors has been particularly difficult.
The rotating shaft of a turbine engine poses another type of challenge since centrifugal forces exceeding 80,000 G's with very high ambient temperatures is routine. Batteries cannot survive these forces and the high speed rotation precludes hardwiring or even slip-ring connections, which don't work reliably at such high RPM for extended periods of time. Furthermore, crystals commonly used for system timing, have not been able to withstand these forces making placement and reading of sensors in such locations difficult.
Thus, a better solution is needed to provide power and to read sensors that may be in inaccessible places or experiencing harsh environments where electric power is limited or where batteries cannot be easily recharged, and this solution is provided by the following patent application.